Apparatus for the burning of solids

ABSTRACT

A system to burn waste materials with essentially complete combustion including a vertical preheating chamber with upper waste inlet and lower outlet, the outlet conducting preheated material into a furnace having a rotating frusto-conical grate with a vertex angle of between 90* and 120* arranged somewhat horizontal so a lowermost surface line is slightly inclined down toward the large inlet end of the grate relative to a horizontal reference. The furnace has an air inlet system which directs a controlled amount of combustion air to a specific limited zone of the grate. The grate, its disposition and the air supply provide a waste material movement and burning to maximize effective use of combustion heat. The system also has apparatus for removing waste solids and gases from the furnace, with components to cool, wash and separate small solids from the waste gas and to utilize controlled quantities of the waste gas for introduction back into the inlet end of the preheating chamber.

United States Patent 1 Schoppe et al.

[ 1 APPARATUS FOR THE BURNING OF SOLIDS [751 lnventorszFritz Schoppe, Munich; George M.

Meyer, Hamburg, both of Germany [73 Assignee: Fritz Schoppe, Munich, Germany [22] Filed: Apr. 27, 1970 [21] Appl. No.: 29,757

Related U.S. Application Data [60] Continuation of Ser. No. 739,977, May 27, 1968, abandoned, which is a continuation of Ser. No. 544,107, May 31, 1966, abandoned, which is a division of Ser. No. 285,983, June 6, 1963, abandoned.

[52] US. Cl ..ll/14 511 Int.Cl ..F23g /06 58 FieldofSearch ..110/s,1s,32,33,

[56] References Cited UNITED STATES PATENTS 285,425 9/1883 Merriman 126/144 549,373 11/1895 Lee 126/181 1,575,350 3/1926 McEwen ..110/ 1,603,601 10/1926 Hejma ..110/ R 2,395,733 2/1946 Fulton ..1 10/35 2,496,156 1/1950 Fulton ..l10/35 1 Apr. 17, 1973 FOREIGN PATENTS OR APPLICATIONS 33,353 12/1964 Finland ..l10/75 R 724,661 l/1932 France 126/181 152944 10/1920 Great Britain ..1 10/35 Primary Examinerl(enneth W. Sprague Attorney-Fred Wiviott and Ralph G. Hohenfeldt [5 7 ABSTRACT A system to burn waste materials with essentially complete combustion including a vertical preheating chamber with upper waste inlet and lower outlet, the

outlet conducting preheated material into a furnace having a rotating frusto-conical grate with a vertex angle of between and arranged somewhat horizontal so a lowermost surface line is slightly inclined down toward the large inlet end of the grate relative to a horizontal reference. The furnace has an air inlet system which directs a controlled amount of combustion air to a specific limited zone of the grate.

The grate, its disposition and the air supply provide a waste material movement and burning to maximize effective use of combustion heat. The system also has apparatus for removing waste solids and gases from the furnace, with components to cool, wash and separate small solids from the waste gas and to utilize controlled quantities of the waste gas for introduction back into the inlet end of the preheating chamber.

34 Claims, 3 Drawing Figures PATENTEUAPR 1 7197s FIG. 1

SHEET 1 OF 3 INVIENTORS FRITZ SCHOPPE Y GEORG M.MEYER M, %j I A ORNEY RELATED APPLICATION This application is a streamlined continuation of the application Ser. No. 739,977, now abandoned, which application is a continuation of the application Ser. No. 544,107, filed May 31, 1966, now abandoned, which application was divided from application Ser. No. 285,983, filed June 6, 1963, now abandoned.

The invention herein relates to a furnace or incinerator device for the burning of solids, such as garbage and similar waste substance.

BACKGROUND In installations for the burning of solids, such as garbage and the like, known prior to this invention, the substances are normally introduced at prevailing atmospheric temperature onto hollow structure, into a rotary kiln or onto another conveying device and conducted of the constant speed and constant direction of forward movement through a furnace. The known installations for burning garbage are extraordinarily large and expensive for two reasons. First, the solids are frequently damp and are difficult to ignite at atmospheric temperature, and therefore must be dried and heated to ignition temperature in the furnace itself, requiring a considerable part of the transport distance in the furnace. Second, with a given speed of conveying, the length of furnace must be so dimensioned, considering the time of sojourn of the combustible proportion, to accomplish complete burning of the largest pieces introduced into the furnace. Because the prior known furnaces had to be dimensioned for the largest pieces introduced, considerable over-dimensioning relative to the small and smallest solid parts occurred.

In rotary furnaces known prior to the present invention, having cylindrical or slightly conical, rotating tubes, the material to be burned is introduced into one endof the rotating tube and passes through in an axial direction. In such furnace, the burned parts are continually separated out by the perforated walls of the rotating tube. A burning zone develops over the length of the rotating tube and is made up of (1) a pre-heatzone, (2) a main burning zone and (3) an after-burning zone. Only easily burnable material of uniform size can be satisfactorily burned in such rotary furnaces. However, if materials composed of a mixture of finer and coarser pieces, which are partly burnable and partly not or scarcely burnable, are placed into those prior art furnaces then the following effect occurs: In the preheat zone, the entire mixture of material is heated up and, in the following main burning zone, the smaller and the easily burnable particles burn completely and are separated out. In the burn-out or aftenburning zone following the main burning zone and located toward the end ofthe rotating tube, the mixture becomes one of unburnable and large, burnable, but still not completely burned pieces. This mixture can no longer be burned, even when the rotating tube is made extraordinarily long, since the temperature in the burnout or after-burning zone can not be kept high enough to completely burn the large, burnable pieces. Rather the blown in combustion air to a considerable extent cools the unburnable pieces so that these must withdraw heat from the burnable pieces, and the combustion process in burnable pieces ceases. Thus, if solid material of non-uniform quality and size, such as, for example, rubbish, is burned in the known rotary furnaces, then, at the end of the rotating tube, a mixture is obtained which still contains a considerable quantity of burnable material.

SUMMARY OF THE INVENTION Accordingly, the primary object ofthe present invention resides in overcoming the above disadvantages by provision of a novel furnace for the burning or incineration of waste solids containing combustible materials, such as garbage and other waste materials wherein only a relatively small installation is needed.

In conjunction with the foregoing object, a further object resides in provision of novel compact furnace structure for conducting waste solids into and through a combustion zone and while the material is in the furnace separating the resulting ashes, and returning the solids containing unburned combustible material back into and through the combustion zone repeatedly until the combustible portions of the solids are completely burned. Due to the repeated return of the unburned partsof the solids to the combustion zone the larger pieces with longer burning duration re-enter and pass through the combustion zone more frequently than do the smaller and more rapidly burning parts. The time of sojourn is automatically adapted to the piece size, without an enlargement of the combustion zone being necessary. In the dimensioning of the furnace it is not necessary to take into consideration either the maximum piece size or the requisite pre-drying and preheating of the solids. The burning installation thus can be made substantially smaller than hitherto has been the practice.

A still further object resides'in providing a novel fur nace construction having a rotatably mounted frustoconical drum grate with a multitude of holes in its peripheral walls equipped with a rotation drive. Material is fed into a front side (open large base) of the drum and the residues of burning are at least partly removable through the multitude of holes in the drum wall. A supply line leads into the furnace for introduction of combustion air. Means mount the drum grate with its axis of rotation coincident with its conical axis and rising toward said open front side at such an angle, that the lowest conical element line of the rotational path of the drum wall is disposed within a location from horizontal to slightly declining toward the open base or front side. This disposition of the special grate results in a rotating flow of the material to be burned, during rotation of the drum, in a zone which, compared to the lowest conical element line position, will be slightly displaced in'the direction of rotation of said drum. The construction also includes a combustion air supply line outlet piece adjacent and effectively disposed under the region of the combustion zone and fitted up closely adjacent the exterior ofthe wall of the drum.

Other novel objects reside in specific structure, such as that which enables tilting of the drum grate to discharge non-burnable residues; a sleeve extension secured to the front opening of the drum grate to increase its capacity for receiving wastes; and a special pin type rim gear and peg type drive gear to avoid interference of heat, trash and other impediments with the rotating gear.

Further novel features and other objects of this invention will become apparent from the following detailed description, discussion and the appended claims taken in conjunction with the accompanying drawings showing a preferred structure and embodiment, in which:

FIG. 1 is a diagrammatic view of an overall trash burning installation in which the furnace invention can be utilized;

' FIG. 2. is a diagrammatic vertical sectional view of the furnace invention with the furnace housing cut away in part to illustrate the drum grate and its disposition relative to ground level or horizontal; and

FIG. 3 is a front elevational view of the cone grate of the furnace taken in the direction of the arrow III of FIG. 2.

The hereinbefore-identified parent application fully discloses a complete system and method for burning of trash and garbage solids and, to the extent necessary for any understanding of the invention in the furnace or burning device being disclosed and claimed herein, the disclosure of said parent application is made a part hereof by reference thereto.

GENERAL In the drawings, FIG. 1, a bunker-shaped container 1, can be filled with solids, 4, e.g., garbage or similar waste substances, through an opening 3, closable by a cover. Container 1 has an upper end air intake communicating with atmosphere and its lower end communicates with a furnace 6 (diagrammatically illustrated in FIGS. 2 and 3 and described in greater detail hereinafter) through a passageway 7 enabling the solids 4 to be introduced continuously or as charges into the furnace. A conduit 8 containing blower 9 leads from the lower end of the container 1 to the air supply duct 19 of the furnace. The blower 9 sucks air through conduit 8 and additionally through a supplemental intake tainer l for preheating, so that these gases together with the air sucked through the air intake and mixed therewith can be conducted in concurrent flow in the direction of the arrow A through the container 1, and

can be introduced through the connecting conduit 8 into the furnace air supply duct 19 (FIG. 2). A blower 1 4, installed in the return conduit 13, may suck air through intake and mix it with the part of the waste combustion gases diverted from duct 12 to container 1.

For effecting a pre-purification of the waste combustion gases emanating from the furnace itself, a constriction 12, as shown in FIG. 2, may be included in the waste gas conduit 12 adjoining the furnace vent opening 39, and spaced somewhat from the vent opening 39. Above the constriction 12 the waste gas conduit widens again. Directly below constriction 12' a pipe 40 enters the cylindrically-shaped waste gas conduit 12 in a tangential fashion so that cold air or waste gases can be introduced or sucked through it into the waste gas conduit 12 and thereby produce a rotary flow in the section below the constriction.

As symbolized in FIG. 2 by arrows, this rotary flow possesses on the conduit wall a flow component caused by the greater density of the cold air, which component is directed towards the interior of the furnace, while at the same time in the nucleus of the rotary flow there exists a flow component of hot waste gases from the furnace directed up into the waste gas conduit. Due to the rotary flow, particles contained in the waste gases are centrifugal radially outward and are conducted downwardly along the wall by the flow component directed towards the interior of the furnace, back into the furnace. Due to the air introduced through the pipe 40 and the resulting mixing in the section above the outlet 39, the pre-purification also includes the burning of any combustible fumes in the waste gases from the furnace.

Shown in FIG. 1, the pre-purified waste gases which pass through conduit 12, are fed to a waste gas cooler 41, wherein cooling water is first sprayed into the waste gases and they leave the cooler through a pipe 42. Cooled waste gases pass on through a conduit 43 to a waste gas washer 44, in which any remaining solids are washed out with the aid of washing water. The washing products are withdrawn from washer 44 in sludge form through a pipe 45. Connected to the waste gas washer 44 is a main blower 46 which draws away the purified waste gases and at the same time provides the suction of air for combustion. Because the main blower 46 is in the vicinity of the outlet end of the solids-burning installation, the latter is completely under negative pressure and waste gases cannot escape from the installation of any point.

From the main blower 46, waste combustion gases are fed to a chimney 47. An axial blower 48 is expediently provided at the lower end of the chimney, so that the latter does not need to be dimensioned excessively large, which blower sucks air and mixes it with the combustion waste gases.

FURNACE its lowermost surface of element line 16 extends substantially horizontally or with an inclination at a small acute angle in relation to the horizontal, as shown in FIG. 2.

Beneath the drum 16 is an air supply duct 19 connected to the conduit 8, arranged and disposed in such fashion that, in relation to the lowermost surface line 16', so its mouth or outlet device 19 is angularly offset in the direction of rotation of the drum 16, i.e., as indicated in FIG. 3 by arrow B. The outlet device 19 at the outlet of the air supply pipe is widened in the manner which may be seen from the drawing with the walls of the outlet 19' shaped for close disposition adjacent the drum periphery and adapted to conform to the external shape thereof. Thus a limited area, offset air supply zone 20 is produced, as is indicated in dotted lines in FIG. 3. The zone 20 extends over a substantial part of the axial length of the drum 16 but its width is only a small extent ofa frusto-conical wall so as to form a confined and rather precisely located combustion zone within the drum 16. The actual outlet mouth of the air supply pipe is expedicntly made with its part directly adjoining the drum periphery as a nozzle which accelerates the flow of air for combustion. In the region of the mouth of the air supply pipe 19 and further extending into the drum an igniting burner (not represented in the drawing) is provided and can be a conventional style of construction.

The useful speed of rotation at the circumference of the drum is about 20-40 m/h (meters per hour). 18'.

Drum 16 is also mounted for pivoting movement about an axis 21 (see FIG. 3), perpendicular to the axis of drum rotation 17, for enabling emptying of larger non-combustible residues than those which will fall through the openings 18 Drum grate 16 possesses a conical or frusto-conical shape, as shown in FIG. 2. The larger diameter end or base of the cone is open for the introduction of the solids 4 to be burned and will be referred to as the open side. The conical angle of the drum preferrably is within a range of from about 90 to l20. On the open side (or the large end) there is attached a countercone-shaped extension 22, which could be a cylindrical sleeve extension if desired, enabling a larger quantity of combustible material to be introduced into the so In the region of the smaller diameter end, the frusto-conical drum I6 is provided with an opening 23, which is closed by a hinged flap 24 mounted on the stationary housing or frame part of the furnace. Opening 23 and flap 24 constitute a closable hatch. By opening flap 24 and pivoting drum 16 about its pivot axis 21 so the small opening 23 is at the bottom of the drum it is possible to empty the larger non-combustible residues from the drum.

The solids to be burned are introduced into the frusto-conical drum 16 through conduit or passage 7 (FIG. I) terminating in a chute 37, FIG. 2, directed toward the open side of the drum. The chute is disposed to one side, angularly offset opposite to the outlet mouth 19' of the air supply duct 19 in relation to a vertical central plane. The solids feeding opening and its location relation to the open side of the drum are characterized in FIG. 3 by an arrow C. Upon rotation of drum 16 in the direction of arrow B in FIG. 3 the waste solids introduced at C are entrained and conducted into and through the combustion zone which is situated above the outlet mouth of the air supply pipe 19. During this movement, smaller particles will be burned while making one passage through the combustion zone and their residue will fall in the form of ash through the openings 18 into an ash-collecting container 25. The larger parts of the solids material roll or fall back again after passing through the combustion zone, undergoing a circulatory movement within the drum as indicated in FIG. 3 by an arrow D, during which movement they pass repeatedly through the combustion zone, namely until their combustible portions are completely burned and are separated out from the drum in the form of ash. The large, non-combustible residues are emptied from time to time by tilting of the drum about its pivot axis 21 in the manner as has been described.

. combustion and burning takes place. Secondly, a

separation of the finer particles from the coarser takes 1 place in the drum; the finer particles in fact remain close to and cling more strongly to the wall of the drum and will thereby be drawn or dragged farther upward and, because the wall is conical, further rearward from the combustion zone than is the coarser material and, in rolling back or falling back, will travel step by step along the tapering wall towards the smaller end of the drum. In this manner the burned small ash particles separate themselves from the large solid particles still to be burned. On the one hand this effect facilitates the dropping of the ash out through the piercings 18 and on the other hand it keeps the combustion zone free from parts already burned.

As appears from the above description, the individual coarser parts of the solids 4 fall back into the combustion zone repeatedly until their combustible portions are completely burned. The time of sojourn of the solids in the drum thus automatically adjusts itself in such fashion that even the largest parts are completely burned, without an especially long combustion time provided by extending a cylinder furnace to thereby as sure a sufficient length of travel in a furnace. It remains only for the completely unburnable residue be taken out of the drum from time to time, as has been described hereinbefore. The drum 16 can be made relatively small and compact, so that the entire burning installation possesses only relatively small dimensions, and complete and rapid burning of combustibles can be achieved in very close quarters.

In order that drum 16 may be rotated, it is surrounded in the region of its major diameter by a pin ring assembly 26, as shown in FIG. 3, consisting of a closed ring 26' spaced a distance from the drum periphery and a plurality of pins 26", arranged at regular angular intervals around the drum periphery and connecting ring 26' with the drum. Engaged with the drum pin ring assembly 26 is a toothed drive wheel (gear) 27 provided with peg toothing. The peg toothing is formed by pins 28 projecting radially from the wheel hub. The peg toothed drive wheel 27 is mounted on a drive shaft 29 connected, for example, through a chain drive (not shown) with a drive motor (not shown). The drum mounted pin ring assembly 26 is rotatably mounted in a frame 30 surrounding the drum, which frame is in turn mounted on fixed furnace structure so it is pivotable about diametrically opposed journals 31 and 31'. The journals 31 and 31 form the aforedescribed horizontal drum pivot axis 21. Drive shaft 29 extends through one journal 31' which, as shown, is made hollow for this purpose.

To enable the rotatable mounting of the drum pin ring assembly 26 on frame 30, guide rollers 32, 34, with crossed axes are freely rotatably by means of journals 33 on frame 30, which can be constructed, for exampie, with straight beams in the manner of a polygon. Rollers 32 bear against the external periphery of the outer pin ring 26', while the rollers 34 engage and support the same ring 26' from beneath.

This type of rotary drive for the drum 18 is extraordinarily sturdy, insensitive to soiling and free from fouling, and furthermore renders possible a simple tilting of the drum. The drum can be held fast in the desired oblique position with rotation axis 17 inclined, in the manner hereinbefore described, in relation to the horizontal, most simply by a cable 35 attached to the frame 30 and wound on a winch (not shown). Upon unwinding of cable 35 from the winch drum, the furnace drum 16, under the force of gravity, will pivot about the journals 31,31 into an emptying position.

Shown in FIG. 2, the drum grate 16 is arranged in a closed housing 36 provided with an entry opening 37 to which the conduit 17 coming from the container 1 (FIG. 1) is connected. The housing 36 is also provided with a closable extraction opening 38, through which ash and residues can be removed. At the top of the housing 36, a vent opening 39 is provided for the flow of the waste combustion gases into the conduit 12.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

l. A device for burning or incinerating garbage and other similar combustible waste materials, comprising: a furnace including a closed housing with an inlet for such.waste materials and a vent outlet for waste combustion gases; a rotatable frusto-conical drum grate; means rotatably mounting said drum grate in said housing; the larger end of said drum grate being open and facing upwardly in position to receive waste from said inlet and the lowermost surface line of said drum grate disposed between a horizontal position and at an upward inclination from said inlet at a small angle to the horizontal; the wall of said drum grate including openings for the passage of ashes from and the flow of air into the drum; an air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior at a zone offset in angular relation with respect to the lowermost surface line of said drum grate in the direction of its rotation, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate at said zone.

2. A furnace device for burning of rubbish and similar solid materials comprising: means for forming a combustion zone in a predetermined location within said furnace; means including a drum grate means which has a frusto-conical shaped interior and is disposed on its side with the side being substantially horizontal and with an inlet located at its large end for conducting solids into said drum grate, means supporting the drum grate for rotation about the cone axis, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on the conical interior surface to thereby enable the coarser materials to be returned closer to large inlet end of the cone than the finer materials so as to subject the solids with greater mass to said predetermined zone of combustion for a longer total period of time than the total period of time that solids with smaller mass are subjected to said predetermined zone of combustion; an annular device secured around the periphery of the inlet at the large end of said drum grate for inhibiting egress of material through said large inlet end during drum grate rotation; means for removing nonburnable residue; means providing continual drum rotation, and means permitting exiting of waste gas.

3. A furnace device for burning of rubbish and similar solid materials comprising: grate means comprising a rotatably mounted drum with a rotation drive means and including a multitude of holes in its peripheral walls, to which drum the material to be burned is feedable into a front side and from which drum the residues of burning are at least partly removable through said multitude of holes; fluid communication means including a supply duct into said furnace for introduction of combustion air; said drum having a truncatedconical form with its base open and constituting said front side; means mounting said drum with its axis of rotation coincident with its conical axis and rising toward said open base of the cone at such an angle, that the lowest conical element line of the rota tional path of the drum wall has a disposition within a location from horizontal to slightly inclined downward toward said open base, in a manner, that a rotating flow of the material to be burned occurs during rotation of the drum in a zone which, compared to the lowest conical element line position, will be slightly displaced in the direction of rotation of said drum; means comprising a combustion air supply duct outlet piece adjacent and effectively disposed under the region of said zone and fitted up closely adjacent the exterior of the wall of said drum; and means enabling exiting of waste combustion gases from said furnace.

4. A device as defined in claim 3 wherein said drive means is adapted to rotate said drum at a speed within the range of from 20-40 m/h.

5. A device as defined in claim 3, wherein the constructive vertex angle of the truncated cone drum falls essentially within a range of from to 6. A device as defined in claim 3, wherein an annular imperforate jacket extension is attached to the open base of said conical drum.

7. A device as claim 6, wherein said extension has a frusto-conical shape converging opposite from the frusto-conical drum convergence.

8. A device as defined in claim 3, wherein said drum includes a closable emptying-hatch in the region of its smallest diameter. j

9. A device as defined in claim 3, wherein means pivotably mount said drum about an axis perpendicular to its axis of rotation.

10. A device as defined in claim 3, wherein said rotation drive means comprising: a ring gear surrounding said drum in the region of its largest diameter; frame means rotatably mounting said drum on its outer periphery; two horizontal, diametrically opposite journals, at least one of which is hollow, mounting said frame for pivotal movement about an axis perpendicular to the drum axis of rotation; a drive shaft passing through a hollow one of said journals; and a driving gear secured on said drive shaft and meshed with said ring gear.

11. A device as defined in claim 10, wherein said ring gear is a pin type rim gear and said driving gear is a peg tooth gear.

12. A device as defined in claim 10, wherein guide rollers are mounted loosely and rotatably in said frame means; said ring gear comprises an outer ring surrounding and spaced away from saiddrum; and said guide rollers receive said outer ring and therethrough provide support for said drum.

13. A device as defined in claim 3, wherein said waste combustion gas exit means comprises an exhaust gas line the entrance of which is situated in the region of and above the open base of said truncated-conical drum; said exhaust line includes a constriction for accelerating the exhaust gas; and means immediately upstream of said constriction are located to introduce air tangentially with reference to the exhaust line flow direction for developing a rotational flow in the region of said exhaust line entrance;

14. A device as defined in claim 3, wherein said grate means comprises means including said drum inhibiting egress of material from the open base of said drum during drum rotation.

15. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having at least one enlarged open end portion, an intermediate portion of said drum grate having a larger diameter than the diameter of said enlarged open end portion, at least a portion of the wall of said drum grate including openings for the passage of ashes from and the flow of air into the drum; an air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior at a zone offset in angular relation with respect to the lowermost surface line of said drum grate in the direction of its rotation, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate at said zone, said vent outlet for the waste combustion gases having a waste gas conduit vertically aligned with the larger open end portion of said drum grate, constriction means formed in said waste gas conduit, tangentially aligned inlet openings in said waste gas conduit below said constriction means, and means for flowing air tangentially through said inlet openings into said waste gas conduit whereby said air flows downwardly on the inside of said waste gas conduit toward the open end portion of said drum grate and the waste combustion gases flow upwardly through the constriction in said waste gas conduit.

16. A device as claimed in claim wherein the waste gases exiting through the vent outlet are diverted to preheat the air being supplied through the air supply conduit.

17. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable tion, an intermediate portion of said drum grate having a larger diameter than the diameter of said enlarged open end portion, at least a portion of the wall of said drum grate including openings for the passage of ashes from and the flow of air into the drum; an air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate, said vent outlet for the waste combustion gases comprises a waste gas conduit vertically aligned with the larger open end portion of said drum grate, constriction means formed in said waste gas conduit, and means for flowing air tangentially into said waste gas conduit whereby said air flows downwardly on the inside of said waste gas conduit toward the open end portion of said drum grate and the waste combustion gases flow upwardly through the constriction in said waste gas conduit.

18. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having at least one enlarged open end portion and at least one smaller open end portion oppositely disposed from said enlarged open end portion, means for closing said smaller open end portion, an intermediate portion of said drum grate having a larger diameter than the diameter of said enlarged open end portion, at least a portion of the wall of said drum grate which is contiguous with the intermediate portion being converging interiorly toward the smaller end portion and including openings for the passage of ashes from and the flow of air into the drum; said drum grate portion being disposed on its side with said side being substantially horizontal; an air supply conduit means located in the furnace for directing air from beneath said drum grate through to the drum grate interior to promote combustion of materials therein, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on the converging portion to thereby enable the coarser materials to be returned closer to the open end of the converging portion than the finer materials.

19. A device as claimed in claim 18, andhaving means for selectively opening the said means for closing said smaller open end portion for thereby clearing out unburnable materials.

20. A device as claimed in claim 19 including means remotely operated and operable on said closing means to open and close said means to clean out said unburna ble materials.

21. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having at least one enlarged open end; means rotatably mounting said drum grate in said housing; the larger open end of said drum grate facing upwardly in position to receive waste from said inlet and the lowermost surface line of said drum grate disposed between a horizontal position and an upward inclination from said inlet of a small angle to the horizontal; the wall of said drum grate including openings for the passage of ashes and the flow of air into the drum; an

air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior at a zone offset in angular relation with respect to the lowermost surface line of said drum grate in the direction of its rotation, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate at said zone.

22. A device as claimed in claim 21 wherein said vent outlet for the waste combustion gases comprises a waste gas conduit vertically aligned with the larger open end portion of said drum grate, constriction means formed in said waste gas conduit, tangentially aligned inlet openings in said waste gas conduit below said constrictriction means, means for flowing air tangentially through said inlet openings into said waste gas conduit whereby said air flows downwardly on the inside of said waste gas conduit toward the open end portion of said drum grate and the waste combustion gases flow upwardly through the constriction in said waste gas conduit.

23. A device as claimed in claim 21 wherein the waste gases exiting through the vent outlet are diverted to preheat the air being supplied through the air supply conduit.

24. A devicefor burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a hollow rotatable drum grate having at least one large open end and which is converging interiorly in an axial direction toward another smaller end; means rotatably mounting said drum grate in said housing for rotation about an axis inclined with respect to the horizontal, said drum grate being disposed on its side with the side being substantially horizontal; the open end of said drum grate facing upwardly in position to receive waste from said inlet; the wall of said drum grate including openings for the passage of ashes and air; means supplying combustion gas to said drum grate through said openings, and said vent outlet for the waste combustion gases comprising a waste gas conduit vertically aligned with the open end of said drum grate, and means on said waste gas conduit for flowing air tangentially therein to cool said waste gas conduit and to complete the combustion of said waste combustion gases, the interior converging shape of said drum grate being such that rotation of said drum grate causes a mixture of coarse and finer materials to be carried on the converging interior to thereby enable the coarser materials to be returned closer to the open end of the converging interior than the finer materials.

25. A device as claimed in claim 24 wherein hatch means are provided in said drum grate at a remotely opposite end from said material inlet which hatch means is selectively operative for clearing out unburnable materials.

26. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having an interiorly converging portions having at least one large open end and a smaller end, said drum grate being disposed on its side with the side being substantially horizontal; means rotatably mounting said drum grate in said housing; the axis of rotation of the drum grate being disposed at an angle to the horizontal whereby the open end of said drum grate faces upwardly in position to receive waste from said inlet; at least one wall of said drum grate including openings for the passage of ashes and the flow of combustion air into the drum; means for supplying combustion air into the housing and into said drum grate through said openings, and means in said vent outlet for completing the combustion of said waste combustion gases, said vent outlet comprising a waste gas conduit vertically aligned with the open end portion of said drum grate, and said means in said waste gas conduit comprises means for flowing air into said waste gas conduit for completing said combustion of the waste gases, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on said converging portion to thereby enable the coarser materials to be returned closer to the large open end of the converging portion than the finer materials.

27. A furnace device for burning of combustible materials comprising: grate means defining a hollow conical structure; means mounting said structure for rotation; rotation drive means coupled with said structure and a multitude of holes in at least one wall of the structure, said structure having an open front side for receiving material that is to be burned and the residues of burning are at least partly removable from said structure through said multitude of holes; means in said furzone in said structure; means mounting said conical structure on its side with its axis of rotation rising toward said open front side and with its bottom side at an acute angle with respect to the horizontal so that material which has passed through the combustion zone flows oppositely to rotation of the drum back into said zone and the coarse materials return to said zone closer to the open-front side of the hollow conical structure than the finer materials; and means enabling exiting of waste combustion gases from said furnace.

28. A furnace device as claimed in claim 27 wherein said grate structure has on a side opposite of said open front side hatch means selectively operative for clearing out unburnable materials.

29. A furnace device as claimed in claim 27 wherein said combustion gas exiting means is a vent outlet vertically aligned with the open front side of said hollow structure, and means in said vent outlet for substantially completing the combustion of the waste gases.

30. A furnace device for burning combustible waste materials comprising: means including combustion air input means for forming a combustion zone through which air is transmissible at a predetermined location within said furnace; means including a drum grate at least a portion of which is conical and is disposed on its side with the side being substantially horizontal said drum grate having an inlet located at one end for conducting solids into and through said predetermined zone of combustion, rotation of said conical drum grate continually returning any unburned portions of the solids back into the predetermined zone of combustion and subjecting the solids with greater mass to return closer to the inlet end of the cone in said predetermined zone of combustion to be retained therein for a longer total period of time than the total period of time that solids with smaller mass are subjected to said predetermined zone of combustion; the drum grate having an axis of rotation inclined upward in the direction of said inlet, means associated with said drum grate and spaced axially from said combustion zone in a direction opposite of said inlet for removing nonburnable residue; means providing continual drum rotation and waste gas exiting means. I

31. A device for burning or incinerating waste materials comprising a furnace, a hollow drum grate having at least a portion which is internally conically shaped and disposed on its side within said furnace for receiving and supporting said material during the burning thereof, the bottom of said conically shaped portion being substantially horizontal, said drum grate having an open front side and having a plurality of openings formed in at least one Wall thereof, means for continually rotating said drum grate about an axis inclined at an acute relative to the horizontal and projecting upward in the direction of said open front side, means for introducing combustion supporting gas through and into the conical portion of said drum grate to the interior thereof to form a combustion zone therein, rotation of the drum grate causing the internal conical surface to continuously move said material outwardly of said zone and back into said zone thereby enabling particles of larger mass to return to the combustion zone closer to the front side of the cone and to remain therein for a longer total period of time than particles of smaller mass and for moving non-burnable residue generally outwardly of said zone in a direction opposite from said open front side.

32. A device for burning or incinerating garbage or other combustible materials, comprising: a rotatable drum grate having an interiorly conical portion; means mounting said drum grate for rotation with its axis at an angle with respect to horizontal, said drum grate being disposed on its side with the side being substantially horizontal; the larger end of said drum grate being generally higher than the smaller end and having an opening to receive waste; the wall of said drum grate including openings for the passage of ashes therefrom and for permitting the flow of air through the wall of the drum grate, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on said conical portion to enable return of the coarser materials generally closer to the larger the of the drum grate than the finer materials.

33. A device for burning or incinerating combustible materials, comprising: a rotatable drum grate having an interiorly conical portion which has a large diameter open combustible material feed end and a smaller diameter end portion axially displaced from said large end, at least a portion of the conical portion of said drum grate having openings for permitting the passages of ashes from the drum grate and the flow of air into the drum grate; an air supply means located for directing air from outside of said drum grate to the drum grate interior; the axis of said conical portion coinciding with the rotational axis thereof and being disposed at an angle with respect to horizontal, said drum grate being disposed on its side with the side being substantially horizontal, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on said conical portion to enable return of the coarser materials generally closer to the larger end of the drum grate than the finer materials.

34. The grate structure set forth in claim 33 comprisa. annular means which are substantially imperforate peripherally, said annular means being tapered op positely from the conical portion and having its larger end fastened coaxially to the larger end of said drum grate and its smaller end open for receiving combustible material therethrough.

UNITED STATES PATENT QFFEICE mmmm'm F eememmw Patent No. 3,727,555 Dated April 17, 1973 Emmet) FRITZ SCHOPPE and GEORGE M MEYER It is certified that error appears in the above-identified patent and that saie Letters Patent are hereby corrected as shown below:

Col, 1, fine 6 of the specification, after "739, 977, insert --fi1ed Ivfllay 27,, 1968--.

Claim 22 C01. 11, 1ine 14, correct spelling of "constrictriction" t0 eonstzr'iction- Signed and sealed this 5th day of February 1974.

{SEAL} Attest:

R 4 .FLETCHER JR. RENE D. TEGIMEYE Officer Acting Commlsslon'er of Patent FORM PC4050 (10-69) USCOMM-DC 60376-P69 i 11.5. GOVI INMEHT PRlNTlNG OFf|C: IBIS 0-36 -534. 

1. A device for burning or incinerating garbage and other similar combustible waste materials, comprising: a furnace including a closed housing with an inlet for such waste mateRials and a vent outlet for waste combustion gases; a rotatable frustoconical drum grate; means rotatably mounting said drum grate in said housing; the larger end of said drum grate being open and facing upwardly in position to receive waste from said inlet and the lowermost surface line of said drum grate disposed between a horizontal position and at an upward inclination from said inlet at a small angle to the horizontal; the wall of said drum grate including openings for the passage of ashes from and the flow of air into the drum; an air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior at a zone offset in angular relation with respect to the lowermost surface line of said drum grate in the direction of its rotation, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate at said zone.
 2. A furnace device for burning of rubbish and similar solid materials comprising: means for forming a combustion zone in a predetermined location within said furnace; means including a drum grate means which has a frusto-conical shaped interior and is disposed on its side with the side being substantially horizontal and with an inlet located at its large end for conducting solids into said drum grate, means supporting the drum grate for rotation about the cone axis, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on the conical interior surface to thereby enable the coarser materials to be returned closer to large inlet end of the cone than the finer materials so as to subject the solids with greater mass to said predetermined zone of combustion for a longer total period of time than the total period of time that solids with smaller mass are subjected to said predetermined zone of combustion; an annular device secured around the periphery of the inlet at the large end of said drum grate for inhibiting egress of material through said large inlet end during drum grate rotation; means for removing nonburnable residue; means providing continual drum rotation, and means permitting exiting of waste gas.
 3. A furnace device for burning of rubbish and similar solid materials comprising: grate means comprising a rotatably mounted drum with a rotation drive means and including a multitude of holes in its peripheral walls, to which drum the material to be burned is feedable into a front side and from which drum the residues of burning are at least partly removable through said multitude of holes; fluid communication means including a supply duct into said furnace for introduction of combustion air; said drum having a truncated-conical form with its base open and constituting said front side; means mounting said drum with its axis of rotation coincident with its conical axis and rising toward said open base of the cone at such an angle, that the lowest conical element line of the rotational path of the drum wall has a disposition within a location from horizontal to slightly inclined downward toward said open base, in a manner, that a rotating flow of the material to be burned occurs during rotation of the drum in a zone which, compared to the lowest conical element line position, will be slightly displaced in the direction of rotation of said drum; means comprising a combustion air supply duct outlet piece adjacent and effectively disposed under the region of said zone and fitted up closely adjacent the exterior of the wall of said drum; and means enabling exiting of waste combustion gases from said furnace.
 4. A device as defined in claim 3 wherein said drive means is adapted to rotate said drum at a speed within the range of from 20- 40 rpm.
 5. A device as defined in claim 3, wherein the constructive vertex angle of the truncated cone drum falls essentially within a range of from 90* to 120*.
 6. A device as defined in claim 3, wherein an annular imperforate jacket extension is attached to the open base of said coNical drum.
 7. A device as claim 6, wherein said extension has a frusto-conical shape converging opposite from the frusto-conical drum convergence.
 8. A device as defined in claim 3, wherein said drum includes a closable emptying-hatch in the region of its smallest diameter.
 9. A device as defined in claim 3, wherein means pivotably mount said drum about an axis perpendicular to its axis of rotation.
 10. A device as defined in claim 3, wherein said rotation drive means comprising: a ring gear surrounding said drum in the region of its largest diameter; frame means rotatably mounting said drum on its outer periphery; two horizontal, diametrically opposite journals, at least one of which is hollow, mounting said frame for pivotal movement about an axis perpendicular to the drum axis of rotation; a drive shaft passing through a hollow one of said journals; and a driving gear secured on said drive shaft and meshed with said ring gear.
 11. A device as defined in claim 10, wherein said ring gear is a pin type rim gear and said driving gear is a peg tooth gear.
 12. A device as defined in claim 10, wherein guide rollers are mounted loosely and rotatably in said frame means; said ring gear comprises an outer ring surrounding and spaced away from said drum; and said guide rollers receive said outer ring and therethrough provide support for said drum.
 13. A device as defined in claim 3, wherein said waste combustion gas exit means comprises an exhaust gas line the entrance of which is situated in the region of and above the open base of said truncated-conical drum; said exhaust line includes a constriction for accelerating the exhaust gas; and means immediately upstream of said constriction are located to introduce air tangentially with reference to the exhaust line flow direction for developing a rotational flow in the region of said exhaust line entrance.
 14. A device as defined in claim 3, wherein said grate means comprises means including said drum inhibiting egress of material from the open base of said drum during drum rotation.
 15. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having at least one enlarged open end portion, an intermediate portion of said drum grate having a larger diameter than the diameter of said enlarged open end portion, at least a portion of the wall of said drum grate including openings for the passage of ashes from and the flow of air into the drum; an air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior at a zone offset in angular relation with respect to the lowermost surface line of said drum grate in the direction of its rotation, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate at said zone, said vent outlet for the waste combustion gases having a waste gas conduit vertically aligned with the larger open end portion of said drum grate, constriction means formed in said waste gas conduit, tangentially aligned inlet openings in said waste gas conduit below said constriction means, and means for flowing air tangentially through said inlet openings into said waste gas conduit whereby said air flows downwardly on the inside of said waste gas conduit toward the open end portion of said drum grate and the waste combustion gases flow upwardly through the constriction in said waste gas conduit.
 16. A device as claimed in claim 15 wherein the waste gases exiting through the vent outlet are diverted to preheat the air being supplied through the air supply conduit.
 17. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having at least one enlarged open end portion, an intermediate poRtion of said drum grate having a larger diameter than the diameter of said enlarged open end portion, at least a portion of the wall of said drum grate including openings for the passage of ashes from and the flow of air into the drum; an air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate, said vent outlet for the waste combustion gases comprises a waste gas conduit vertically aligned with the larger open end portion of said drum grate, constriction means formed in said waste gas conduit, and means for flowing air tangentially into said waste gas conduit whereby said air flows downwardly on the inside of said waste gas conduit toward the open end portion of said drum grate and the waste combustion gases flow upwardly through the constriction in said waste gas conduit.
 18. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having at least one enlarged open end portion and at least one smaller open end portion oppositely disposed from said enlarged open end portion, means for closing said smaller open end portion, an intermediate portion of said drum grate having a larger diameter than the diameter of said enlarged open end portion, at least a portion of the wall of said drum grate which is contiguous with the intermediate portion being converging interiorly toward the smaller end portion and including openings for the passage of ashes from and the flow of air into the drum; said drum grate portion being disposed on its side with said side being substantially horizontal; an air supply conduit means located in the furnace for directing air from beneath said drum grate through to the drum grate interior to promote combustion of materials therein, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on the converging portion to thereby enable the coarser materials to be returned closer to the open end of the converging portion than the finer materials.
 19. A device as claimed in claim 18, and having means for selectively opening the said means for closing said smaller open end portion for thereby clearing out unburnable materials.
 20. A device as claimed in claim 19 including means remotely operated and operable on said closing means to open and close said means to clean out said unburnable materials.
 21. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having at least one enlarged open end; means rotatably mounting said drum grate in said housing; the larger open end of said drum grate facing upwardly in position to receive waste from said inlet and the lowermost surface line of said drum grate disposed between a horizontal position and an upward inclination from said inlet of a small angle to the horizontal; the wall of said drum grate including openings for the passage of ashes and the flow of air into the drum; an air supply conduit located in the furnace for supplying air from beneath said drum grate through to the drum grate interior at a zone offset in angular relation with respect to the lowermost surface line of said drum grate in the direction of its rotation, said air supply conduit having an outlet mouth located adjacent to the exterior of the drum grate at said zone.
 22. A device as claimed in claim 21 wherein said vent outlet for the waste combustion gases comprises a waste gas conduit vertically aligned with the larger open end portion of said drum grate, constriction means formed in said waste gas conduit, tangentially aligned inlet openings in said waste gas conduit below said constrictriction means, means for flowing air tAngentially through said inlet openings into said waste gas conduit whereby said air flows downwardly on the inside of said waste gas conduit toward the open end portion of said drum grate and the waste combustion gases flow upwardly through the constriction in said waste gas conduit.
 23. A device as claimed in claim 21 wherein the waste gases exiting through the vent outlet are diverted to preheat the air being supplied through the air supply conduit.
 24. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a hollow rotatable drum grate having at least one large open end and which is converging interiorly in an axial direction toward another smaller end; means rotatably mounting said drum grate in said housing for rotation about an axis inclined with respect to the horizontal, said drum grate being disposed on its side with the side being substantially horizontal; the open end of said drum grate facing upwardly in position to receive waste from said inlet; the wall of said drum grate including openings for the passage of ashes and air; means supplying combustion gas to said drum grate through said openings, and said vent outlet for the waste combustion gases comprising a waste gas conduit vertically aligned with the open end of said drum grate, and means on said waste gas conduit for flowing air tangentially therein to cool said waste gas conduit and to complete the combustion of said waste combustion gases, the interior converging shape of said drum grate being such that rotation of said drum grate causes a mixture of coarse and finer materials to be carried on the converging interior to thereby enable the coarser materials to be returned closer to the open end of the converging interior than the finer materials.
 25. A device as claimed in claim 24 wherein hatch means are provided in said drum grate at a remotely opposite end from said material inlet which hatch means is selectively operative for clearing out unburnable materials.
 26. A device for burning or incinerating combustible waste materials, comprising: a furnace including a housing with an inlet for such waste materials and a vent outlet for waste combustion gases; a rotatable drum grate having an interiorly converging portions having at least one large open end and a smaller end, said drum grate being disposed on its side with the side being substantially horizontal; means rotatably mounting said drum grate in said housing; the axis of rotation of the drum grate being disposed at an angle to the horizontal whereby the open end of said drum grate faces upwardly in position to receive waste from said inlet; at least one wall of said drum grate including openings for the passage of ashes and the flow of combustion air into the drum; means for supplying combustion air into the housing and into said drum grate through said openings, and means in said vent outlet for completing the combustion of said waste combustion gases, said vent outlet comprising a waste gas conduit vertically aligned with the open end portion of said drum grate, and said means in said waste gas conduit comprises means for flowing air into said waste gas conduit for completing said combustion of the waste gases, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on said converging portion to thereby enable the coarser materials to be returned closer to the large open end of the converging portion than the finer materials.
 27. A furnace device for burning of combustible materials comprising: grate means defining a hollow conical structure; means mounting said structure for rotation; rotation drive means coupled with said structure and a multitude of holes in at least one wall of the structure, said structure having an open front side for receiving material that is to be burned and the residues of burning are at least partly removable from said structure through said multiTude of holes; means in said furnace for introduction of combustion air which is directed from the outside through said structure to its inside the entry region of the air creating a combustion zone in said structure; means mounting said conical structure on its side with its axis of rotation rising toward said open front side and with its bottom side at an acute angle with respect to the horizontal so that material which has passed through the combustion zone flows oppositely to rotation of the drum back into said zone and the coarse materials return to said zone closer to the open front side of the hollow conical structure than the finer materials; and means enabling exiting of waste combustion gases from said furnace.
 28. A furnace device as claimed in claim 27 wherein said grate structure has on a side opposite of said open front side hatch means selectively operative for clearing out unburnable materials.
 29. A furnace device as claimed in claim 27 wherein said combustion gas exiting means is a vent outlet vertically aligned with the open front side of said hollow structure, and means in said vent outlet for substantially completing the combustion of the waste gases.
 30. A furnace device for burning combustible waste materials comprising: means including combustion air input means for forming a combustion zone through which air is transmissible at a predetermined location within said furnace; means including a drum grate at least a portion of which is conical and is disposed on its side with the side being substantially horizontal said drum grate having an inlet located at one end for conducting solids into and through said predetermined zone of combustion, rotation of said conical drum grate continually returning any unburned portions of the solids back into the predetermined zone of combustion and subjecting the solids with greater mass to return closer to the inlet end of the cone in said predetermined zone of combustion to be retained therein for a longer total period of time than the total period of time that solids with smaller mass are subjected to said predetermined zone of combustion; the drum grate having an axis of rotation inclined upward in the direction of said inlet, means associated with said drum grate and spaced axially from said combustion zone in a direction opposite of said inlet for removing nonburnable residue; means providing continual drum rotation and waste gas exiting means.
 31. A device for burning or incinerating waste materials comprising a furnace, a hollow drum grate having at least a portion which is internally conically shaped and disposed on its side within said furnace for receiving and supporting said material during the burning thereof, the bottom of said conically shaped portion being substantially horizontal, said drum grate having an open front side and having a plurality of openings formed in at least one wall thereof, means for continually rotating said drum grate about an axis inclined relative to the horizontal and projecting upward in the direction of said open front side, means for introducing combustion supporting gas through and into the conical portion of said drum grate to the interior thereof to form a combustion zone therein, rotation of the drum grate causing the internal conical surface to continuously move said material outwardly of said zone and back into said zone thereby enabling particles of larger mass to return to the combustion zone closer to the front side of the cone and to remain therein for a longer total period of time than particles of smaller mass and for moving non-burnable residue generally outwardly of said zone in a direction opposite from said open front side.
 32. A device for burning or incinerating garbage or other combustible materials, comprising: a rotatable drum grate having an interiorly conical portion; means mounting said drum grate for rotation with its axis at an angle with respect to horizontal, said drum grate being disposed on its side with the side being substAntially horizontal; the larger end of said drum grate being generally higher than the smaller end and having an opening to receive waste; the wall of said drum grate including openings for the passage of ashes therefrom and for permitting the flow of air through the wall of the drum grate, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on said conical portion to enable return of the coarser materials generally closer to the larger end of the drum grate than the finer materials.
 33. A device for burning or incinerating combustible materials, comprising: a rotatable drum grate having an interiorly conical portion which has a large diameter open combustible material feed end and a smaller diameter end portion axially displaced from said large end, at least a portion of the conical portion of said drum grate having openings for permitting the passages of ashes from the drum grate and the flow of air into the drum grate; an air supply means located for directing air from outside of said drum grate to the drum grate interior; the axis of said conical portion coinciding with the rotational axis thereof and being disposed at an angle with respect to horizontal, said drum grate being disposed on its side with the side being substantially horizontal, rotation of said drum grate causing a mixture of coarse and finer materials to be carried on said conical portion to enable return of the coarser materials generally closer to the larger end of the drum grate than the finer materials.
 34. The grate structure set forth in claim 33 comprising: a. annular means which are substantially imperforate peripherally, said annular means being tapered oppositely from the conical portion and having its larger end fastened coaxially to the larger end of said drum grate and its smaller end open for receiving combustible material therethrough. 